This invention relates to the field of catheters and, more particularly, relates to those catheters utilized for injecting fluids into a mammalian body.
Present-day catheters generally have a main body section in which the outside and inside diameters remain the same along the whole length of this section. These catheters may have a tip portion wherein the outside and inside diameters taper at the distal end. Illustrative are Cope, U.S. Pat. No. 4,405,314 (drainage catheter); Birtwell, U.S. Pat. No. 3,094,124 (arterial catheter); and Levy, U.S. Pat. No. 701,587 (catheter). In French Patent No. 2,119,261 there are shown configurations in which the inside and outside diameters vary along the length of the catheter.
Some catheters and other medical devices have a relatively small portion at the distal end in which the inside diameter diverges. Illustrative are Bazell et al., U.S. Pat. No. 3,890,976 (catheter tip assembly); Calabrese, U.S. Pat. No. 4,335,718 (needle cannula); Sheridan, U.S. Pat. No. 3,400,7814 (nasal cannula); Fresevins German, No. 05 2811 278 (cannula); and Poitras, U.S. Pat. No. 2,638,897 (flared exit phlebotomy needle). The outside diameters of these devices at the distal end may diverge, taper, or remain constant.
In Flamm, U.S. Pat. No. 2,734,665, there is a fluid device having a nozzle wherein the inside diameter varies over the length of the nozzle from a minimum at the proximal end to a maximum at the distal end. The outside diameter may taper toward the distal end. This nozzle is relatively short when compared to the length of a catheter. There is no indication that greater flow rate can be obtained with this configuration.
When injecting fluids into a mammalian body, e.g., a human body, it is often desirable to inject the fluids as rapidly as possible. However, due to the constraints imposed by trauma or the size of the vessels, the catheters used for injecting the fluids can only be of limited diameter. Flow rate is also limited by the strength of the catheter material since the wall thickness can only be so thin, dependent of course on the material, before the catheter bursts. No attempt has been made to alter the inside diameter along the length of the catheter to increase the flow rate. Accordingly, the flow rate possible for injecting fluids is necessarily limited with present-day catheters. It thus becomes desirable to optimize the design of the catheter so as to increase the flow rate.
It does not appear that any of the above prior art suggests a catheter for injecting fluids having an inside diameter which varies over the length of the catheter from a minimum at the proximal end to a maximum at the distal end. Nor does any of the prior art suggest varying the catheter configuration so as to increase the flow rate.
Accordingly, it is an object of this invention to optimize the design of the catheter for injecting fluids.
It is another object of the invention to vary the catheter configuration so as to increase the flow rate possible.
It is a further object of the invention to have a catheter that will increase the flow rate when injecting fluids but will not increase the amount of vascular trauma.
These and other objects of the invention will become apparent from reference to the following description considered in conjunction with the accompanying figures.